In directional drilling, the angle of the bottom hole assembly (BHA) is typically fixed on the surface before lowering the BHA down hole. The borehole drilling operation may then be performed by circulating fluid (mud) through the drill pipe which in turn rotates the mud motor and, thus, the drill bit.
As the drilling process continues, an operation typically referred to as sliding may occur where the rotating drill bit is being pushed with the drill string while the fixed angle at the motor assembly keeps increasing the angle. Excessive build up of the angle is controlled by what is known as “rotating and sliding”. The “rotating and sliding” operation constitutes rotating the drill pipe from a rotary table at the surface while simultaneously pumping the mud through the drill pipe to rotate the mud motor. This “rotating and sliding” operation results in a corkscrew effect such as a “spiral borehole” or “corkscrew borehole”. The resulting corkscrew effect in the borehole may reduce the accuracy of downhole measurements.